Transmission power control method, and mobile communication system

ABSTRACT

A transmission power control method for controlling a transmission power of an E-HICH for uplink user data transmitted from a cell controlled by a radio base station to a mobile station, includes: notifying, from a radio network controller to at least one radio base station controlling a first cell and a second cell, offsets between the transmission power of the E-HICH and a transmission power of a DPCH, when a mobile station is performing a soft-handover with the first and second cell; determining, at the first cell, a transmission power of a first E-HICH based on a notified offset, and transmitting the first E-HICH to the mobile station using the determined transmission power; and determining, at the second cell, transmission power of a second E-HICH based on a notified offset, and transmitting the second E-HICH to the mobile station using the determined transmission power.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. P2005-274648, filed on Aug.24, 2005; the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a transmission power control method anda mobile communication system for controlling a transmission power of atransmission acknowledgement channel for uplink user data, which istransmitted from a cell controlled by a radio base station to a mobilestation.

2. Description of the Related Art

In a conventional mobile communication system, when setting a DedicatedPhysical Channel (DPCH) between a mobile station UE and a radio basestation Node B, a radio network controller RNC is configured todetermine a transmission rate of uplink user data, in consideration ofhardware resources for receiving of the radio base station Node B(hereinafter, hardware resource), a radio resource in an uplink (aninterference volume in an uplink), a transmission power of the mobilestation UE, a transmission processing performance of the mobile stationUE, a transmission rate required for an upper application, or the like,and to notify the determined transmission rate of the uplink user databy a message of a layer-3 (Radio Resource Control Layer) to both of themobile station UE and the radio base station Node B.

Here, the radio network controller RNC is provided at an upper level ofthe radio base station Node B, and is an apparatus configured to controlthe radio base station Node B and the mobile station UE.

In general, data communications often cause burst traffic compared withvoice communications or TV communications. Therefore, it is preferablethat a transmission rate of a channel used for the data communicationsis changed fast.

However, as shown in FIG. 1, the radio network controller RNC integrallycontrols a plurality of radio base stations Node B in general.Therefore, in the conventional mobile communication system, there hasbeen a problem that it is difficult to perform fast control for changingof the transmission rate of uplink user data (for example, perapproximately 1 through 100 ms), due to the increase of processing loadand processing delay in the radio network controller RNC.

In addition, in the conventional mobile communication system, there hasbeen also a problem that costs for implementing an apparatus and foroperating a network are substantially increased even if the fast controlfor changing of the transmission rate of the uplink user data can beperformed.

Therefore, in the conventional mobile communication system, control forchanging of the transmission rate of the uplink user data is generallyperformed on the order from a few hundred ms to a few seconds.

Accordingly, in the conventional mobile communication system, when burstdata transmission is performed as shown in FIG. 2A, the data aretransmitted by accepting low-speed, high-delay, and low-transmissionefficiency as shown in FIG. 2B, or, as shown in FIG. 2C, by reservingradio resources for high-speed communications to accept that radiobandwidth resources in an unoccupied state and hardware resources in theradio base station Node B are wasted.

It should be noted that both of the above-described radio bandwidthresources and hardware resources are applied to the vertical radioresources in FIGS. 2B and 2C.

Therefore, the 3rd Generation Partnership Project (3GPP) and the 3rdGeneration Partnership Project 2 (3GPP2), which are internationalstandardization organizations of the third generation mobilecommunication system, have discussed a method for controlling radioresources at high speed in a layer-1 and a media access control (MAC)sub-layer (a layer-2) between the radio base station Node B and themobile station UE, so as to utilize the uplink radio resourceseffectively. Such discussions or discussed functions will be hereinafterreferred to as “Enhanced Uplink (EUL)”.

Referring to FIG. 3, the mobile communication system, to which the“Enhanced Uplink” is applied, is explained.

As shown in an example of FIG. 3, in the mobile communication system, acell, which is controlled by a radio base station Node B, is configuredto transmit an “Enhanced HARQ Acknowledgement Indicator Channel(B-HICH)” which is a transmission acknowledge channel, in order toperform a retransmission control of the uplink user data, i.e., “HybridAutomatic Repeat Request (HARQ)”.

In other words, in the above mobile communication system, the cell,which is controlled by the radio base station Node B, is configured toperform an error detection check (“Cyclic Redundancy Check” CRC) of theuplink user data transmitted via an “Enhanced Dedicated Physical DataChannel (E-DPDCH)”, and to notify an “ACK” or a “NACK” to the mobilestation UE using the E-HICH, so as to perform the retransmission controlof the uplink user data of the mobile station UE.

To be more specific, as shown in FIG.3, the mobile station UE, which hastransmitted an E-DPDCH #1 to a cell #2, is configured to transmit thesubsequent E-DPDCH to the cell #2, upon receiving of an E-HICH #1 (ACK)from the cell #2.

On the other hand, the mobile station UE is configured to retransmit theE-DPDCH #1 to the cell #2, upon receiving of the E-HICH (NACK) from thecell #2.

Further, in the above mobile communication system, a closed looptransmission power control using a “Transmit Power Control (TPC)command” is known, as an example of the transmission power controlmethod for a downlink dedicated physical channel (herein after, DPCH)transmitted from the radio base station Node B.

Referring to FIG. 4A, the closed loop transmission power control usingthe TPC command is described.

As shown in FIG. 4A, the mobile station UE, which has received adownlink DPCH transmitted from the cell #2, is configured to determinethe increase/decrease of a transmission power of the downlink DPCH inthe cell #2 controlled by the radio base station Node B, based on thetransmission power of the received downlink DPCH. Then, the mobilestation UE is configured to transmit the determined result of theincrease/decrease of the transmission power of the downlink DPCH to thecell #2, using the TPC command (for example, UP command/Down Command).

In addition, the cell #2 is configured to control the transmission powerof the downlink DPCH to be transmitted to the mobile station UE, usingthe TPC command transmitted from the mobile station UE.

In addition, in the above mobile communication system, the cell #2 isconfigured to determine the transmission power of the E-HICH, based onthe transmission power of the downlink DPCH and a predetermined offset(an E-HICH offset).

As described above, in the mobile communication system, the receptionpower of the downlink DPCH in the mobile station UE will be improved bythe transmission power control using the TPC command, and therefore, thereception power of the E-HICH, which depends on the downlink DPCH, willbe also improved.

Next, referring to FIG. 4B, the transmission power control using the TPCcommand in the mobile communication system in which soft-handover (SHO)is performed is described.

In the above mobile communication system, as shown in FIG. 4B, when themobile station UE is performing the SHO by establishing radio links withthe cell #3 as well as the cell #4, and when the mobile station UEreceives the same DPCHs #1 transmitted from the cell #3 and the cell #4,the mobile station UE is configured to combine the DPCH #1 received fromthe cell #3 and the DPCH#1 received from the cell #4, so as to determinethe increase/decrease of the transmission power of the DPCH #1 in bothof the cell #3 and the cell #4, based on the reception power of thecombined DPCH #1.

Then, the mobile station UE is configured to transmit the determinedresult of the increase/decrease of the transmission power of the DPCH #1to the both of the cell #3 and the cell #4, using the TPC command.

In addition, in the above mobile communication system, the transmissionpower of the E-HICH #1 transmitted from the cell #3 is configured to bedetermined, based on the transmission power of the DPCH #1 transmittedfrom the cell #3 and the predetermined offset (the E-HICH offset).

In addition, the transmission power of the E-HICH #2 transmitted fromthe cell #4 is configured to be determined, based on the transmissionpower of the DPCH #1 transmitted from the cell #4 and the predeterminedoffset (the E-HICH offset).

Further, as shown in FIG. 4B, in the above mobile communication system,if the mobile station UE is performing the SHO by establishing the radiolinks with the cell #3 as well as the cell #4, and if the receptionpower of the DPCH #1 transmitted from the cell #3 is good enough, evenwhen the reception power of the DPCH #1 transmitted from the cell #4 isinsufficient, the reception power of the combined DPCH #1 will besufficient for the mobile station UE.

Therefore, in the above mobile communication system, the mobile stationUE can receive the DPCH#1, if the reception power of the DPCH #1transmitted from the cell #3 is good enough, even when the receptionpower of the DPCH #1 transmitted from the cell #4 is insufficient.

Accordingly, in such a condition, the transmission power of the DPCH #1does not have to be increased, and the mobile station UE is configurednot to transmit the TPC command (for example, UP command) for increasingthe transmission power of the DPCH #1 transmitted from the cell #4.

However, in the above condition, as shown in FIG. 5, the transmissionpower of the E-HICH #2 transmitted from the cell #4 is depending on thetransmission power of the DPCH #1 transmitted from the cell #4, so thatthe reception power of the E-HICH #2 will be insufficient, when thereception power of the DPCH #1 transmitted from the cell #4 isinsufficient in the mobile station UE.

Therefore, in the above mobile communication system, when the mobilestation UE is performing the SHO by establishing the radio links withthe cell #3 as well as the cell #4, the mobile station UE can receivethe E-HICH #1 transmitted from the cell #3, however the mobile stationUE cannot receive the E-HICH #2 transmitted from the cell #4.

Accordingly, in the case as shown in FIG. 5, there has been a problemthat the mobile station UE can receive the E-HICH #1 (NACK) and themobile station UE can not receive the E-HICH #2 (ACK), even when thecell #3 transmits the E-HICH #1 (NACK) in response to the E-DPDCH #1transmitted from the mobile station UE, and the cell #4 transmits theE-HICH #2 (ACK) in response to the E-DPDCH #1 transmitted from themobile station UE.

Therefore, in such a case, the mobile station UE does not transmit thesubsequent uplink user data, but the mobile station UE retransmits theE-DPDCH #1 to the cell #4 unnecessarily.

BRIEF SUMMARY OF THE INVENTION

The present invention has been made considering the problems, and itsobject is to provide a transmission power control method and a mobilecommunication system, in which E-HICHs can be certainly reached to amobile station UE, even when the mobile station UE is performing thesoft-handover.

A first aspect of the present invention is summarized as a transmissionpower control method for controlling a transmission power of atransmission acknowledgement channel for uplink user data which istransmitted from a cell controlled by a radio base station to a mobilestation, including: notifying, from a radio network controller to atleast one radio base station controlling a first cell and a second cell,offsets between the transmission power of the transmissionacknowledgement channel and a transmission power of a dedicated physicalchannel, when a mobile station is performing a soft-handover with thefirst cell and the second cell; determining, at the first cell, atransmission power of a first transmission acknowledge channel based ona notified offset, and transmitting the first transmission acknowledgechannel to the mobile station using the determined transmission power;and determining, at the second cell, transmission power of a secondtransmission acknowledge channel based on a notified offset, andtransmitting the second transmission acknowledge channel to the mobilestation using the determined transmission power.

In the first aspect, the radio network controller can be configured tonotify, to at least one radio base station controlling the first celland the second cell, the offsets between the transmission power of thetransmission acknowledgement channel and the transmission power of thededicated physical channel, when the mobile station is not performing asoft-handover with the first cell and the second cell.

A second aspect of the present invention is summarized as a mobilecommunication system for controlling transmission power of atransmission acknowledgement channel for uplink user data which istransmitted from a cell controlled by a radio base station to a mobilestation; wherein a radio network controller is configured to notify, toat least one radio base station controlling a first cell and a secondcell, offsets between a transmission power of a transmissionacknowledgement channel and a transmission power of a dedicated physicalchannel, when a mobile station is performing a soft-handover with thefirst cell and the second cell; the first cell is configured todetermine a transmission power of a first transmission acknowledgechannel based on a notified offset, and to transmit the firsttransmission acknowledge channel to the mobile station using thedetermined transmission power, and the second cell is configured todetermine a transmission power of a second transmission acknowledgechannel based on a notified offset, and to transmit the secondtransmission acknowledge channel to the mobile station using thedetermined transmission power.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is diagram of an entire configuration of a general mobilecommunication system.

FIGS. 2A to 2C are diagrams for explaining a method for controlling atransmission power in a conventional mobile communication system.

FIG. 3 is a diagram of an entire configuration of the conventionalmobile communication system.

FIGS. 4A and 4B are diagrams for explaining a transmission power controlmethod in the conventional mobile communication system.

FIG. 5 is a diagram for explaining the transmission power control methodin the conventional mobile communication system.

FIG. 6 is a functional block diagram of a mobile station in the mobilecommunication system according to the first embodiment of the presentinvention.

FIG. 7 is a functional block diagram of a baseband signal processingsection of the mobile station in the mobile communication systemaccording to the first embodiment of the present invention.

FIG. 8 is a diagram for explaining functions of the baseband signalprocessing section of the mobile station in the mobile communicationsystem according to the first embodiment of the present invention.

FIG. 9 is a functional block diagram of a MAC-e functional section inthe baseband signal processing section of the mobile station in themobile communication system according to the first embodiment of thepresent invention.

FIG. 10 is a graph illustrating an operation of four channel stop andwait protocol performed by an HARQ processing section in the MAC-efunctional section in the baseband signal processing section of themobile station in the mobile communication system according to the firstembodiment of the present invention.

FIG. 11 is a functional block diagram of a layer-1 functional section inthe baseband signal processing section of the mobile station in themobile communication system according to the first embodiment of thepresent invention.

FIG. 12 is a diagram for explaining functions of the layer-1 functionalsection in the baseband signal processing section of the mobile stationin the mobile communication system according to the first embodiment ofthe present invention.

FIG. 13 is a functional block diagram of a radio base station accordingto the first embodiment of the present invention.

FIG. 14 is a functional block diagram of a baseband signal processingsection in the radio base station of the mobile communication systemaccording to the first embodiment of the present invention.

FIG. 15 is a functional block diagram of a layer-1 functional section inthe baseband signal processing section in the radio base station of themobile communication system according to the first embodiment of thepresent invention.

FIG. 16 is a functional block diagram of a MAC-e functional section inthe baseband signal processing section in the radio base station of thecommunication system according to the first embodiment of the presentinvention.

FIG. 17 is a functional block diagram of a radio network controller ofthe mobile communication system according to the first embodiment of thepresent invention.

FIG. 18 is a sequence diagram showing an example of a transmission powercontrol method according to the first embodiment of the presentinvention.

FIG. 19 is a sequence diagram showing an example of the transmissionpower control method according to the first embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION Configuration of MobileCommunication System According to First Embodiment of the PresentInvention

Referring to FIGS. 6 to 17, a configuration of a mobile communicationsystem according to a first embodiment of the present invention will bedescribed.

It should be noted that, the mobile communication system according tothis embodiment is designed in order to increase a communicationperformance such as a communication capacity, a communication qualityand the like. Further, the mobile communication system according to thisembodiment can be applied to “W-CDMA” and “CDMA2000” of the thirdgeneration mobile communication system.

An example of general configuration of a mobile station UE according tothis embodiment is shown in FIG. 6.

As shown in FIG. 6, the mobile station UE is provided with a businterface 11, a call processing control section 12, a baseband signalprocessing section 13, a transmitter-receiver section 14, and atransmission-reception antenna 15. In addition, the mobile station UEcan be configured to include an amplifier section (not shown in FIG. 4).

However, these functions do not have to be independently present ashardware. That is, these functions can be partly or entirely integrated,or can be configured through a process of software.

In FIG. 7, a functional block of the baseband signal processing section13 is shown.

As shown in FIG. 7, the baseband signal processing section 13 isprovided with an upper layer functional section 131, a RLC functionalsection 132, a MAC-d functional section 133, a MAC-e functional section134, and a layer-1 functional section 135.

The RLC functional section 132 is configured to work as a RLC sublayer.The layer-1 functional section 135 is configured to work as a layer-1.

As shown in FIG. 8, the RLC functional section 132 is configured todivide an application data (RLC SDU), which is received from the upperlayer functional section 131, into PDUs of a predetermined PDU size.Then, the RLC functional section 132 is configured to generate RLC PDUsby adding a RLC header used for a sequence control processing,retransmission processing, and the like, so as to pass the RLC PDus tothe MAC-d functional section 133.

Here, a pipeline works as a bridge between the RLC functional section132 and the MAC-d functional section 133 is a “logical channel” Thelogical channel is classified based on the contents of data to betransmitted/received, and when a communication is performed, it ispossible to establish a plurality of logical channels in one connection.In other words, when the communication is performed, it is possible totransmit/receive a plurality of data with different contents (forexample, control data and user data, or the like) logically in parallel.

The MAC-d functional section 133 is configured to multiplex the logicalchannels, and to add a MAC-d header associated with the multiplex of thelogical channels, so as to generate a MAC-d PDU. A plurality of MAC-dPDUs are transferred from the MAC-d functional section 133 to the MAC-efunctional section 134 as MAC-d flow.

The MAC-e functional section 134 is configured to assemble a pluralityof MAC-d PDUs which are received from the MAC-d functional section 133as MAC-d flow, and to add a MAC-e header to the assembled MAC-d PDU, soas to generate a transport block. Then, the MAC-e functional section 134is configured to pass the generated transport block to the layer-1functional section 135 through a transport channel.

In addition, the MAC-e functional section 134 is configured to work as alower layer of the MAC-d functional section 133, and to implement theretransmission control function according to Hybrid ARQ (HARQ) and thetransmission rate control function.

Specifically, as shown in FIG. 9, the MAC-e functional section 134 isprovided with a multiplex section 134 a, an E-TFC electing section 134b, and an HARQ processing section 134 c.

The multiplex section 134 a is configured to perform a multiplexprocessing to the uplink user data, which is received from the MAC-dfunctional section 133 as MAC-d flow, based on a “Enhanced—TransportFormat Indicator (E-TFI)” notified from the E-TFC selecting section 134b, so as to generate uplink user data (a Transport Block) to betransmitted via a transport channel (E-DCH). Then, the multiplex section134 a is configured to transmit the generated uplink user data(Transport Block) to the HARQ processing section 134 c.

Hereinafter, the uplink user data received as MAC-d flow is indicated asthe “uplink user data (MAC-d flow)”, and the uplink user data to betransmitted via the transport channel (E-DCH) is indicated as the“uplink user data (E-DCH)”.

The E-TFI is an identifier of a transport format, which is a format forproviding the transport block on the transport channel (E-DCH) per TTI,and the E-TFI is added to the MAC-e header.

The multiplex section 134 a is configured to determine a transmissiondata block size to be applied for the uplink user data based on theE-TFI notified from the E-TFC selecting section 134 b, and to notify thedetermined transmission data block size to the HARQ processing section134 c.

In addition, when the multiplex section 134 a receives the uplink userdata from the MAC-d functional section 133 as MAC-d flow, the multiplexsection 134 a is configured to notify, to the B-TFC selecting section134 b, E-TFC selecting information for selecting a transport format forthe received uplink user data.

Here, the E-TFC selecting information includes data size and priorityclass of the uplink user data, or the like.

The HARQ processing section 134 c is configured to perform theretransmission control processing for the “uplink user data (E-DCH)”according to the “N channel stop and wait (N-SAW) protocol”, based onACK/NACK for the uplink user data notified from the layer-1 functionalsection 135. An example for operations of the “4 channel stop and waitprotocol” is shown in FIG. 10.

In addition, the HARQ processing section 134 c is configured totransmit, to the layer-1 functional section 135, the “uplink user data(E-DCH)” received from the multiplex section 134 a, and HARQ information(for example, a number for retransmission, and the like) used for theHARQ processing.

The E-TFC selecting section 134 b is configured to determine thetransmission rate of the uplink user data by selecting the transportformat (E-TF) to be applied to the “uplink user data (E-DCH)”.

Specifically, the E-TFC selecting section 134 b is configured todetermine whether the transmission of the uplink user data should beperformed or stopped, based on scheduling information, the amount ofdata in MAC-d PDU, the condition of hardware resource of the radio basestation Node B, and the like.

The scheduling information (such as absolute transmission rate and arelative transmission rate of the uplink user data) is received from theradio base station Node B, the amount of data in MAC-d PDU (such as datasize of the uplink user data) is passed from the MAC-d functionalsection 133, and the condition of hardware resource of the radio basestation Node B is controlled in the MAC-e functional section 134.

Then, the E-TFC selection section 134 b is configured to select thetransport format (E-TF) to be applied to transmission of the uplink userdata, and to notify the E-TFI for identifying the selected transportformat to the layer-1 functional section 135 and the multiplex section134 a.

For example, the E-TFC selecting section 134 b is configured to storethe transmission rate of uplink user data in association with thetransport format, to update the transmission rate of uplink user databased on the scheduling information from the layer-1 functional section135, and to notify, to the layer-1 functional section 135 and themultiplex section 134 a, the E-TFI for identifying the transport formatwhich is associated with the updated transmission rate of uplink userdata.

Here, when the E-TFC selecting section 134 b receives the absolutetransmission rate of the uplink user data from the serving cell for themobile station UE via the E-AGCH as the scheduling information, theE-TFC selecting section 134 b is configured to change the transmissionrate of the uplink user data to the received absolute transmission rateof the uplink user data.

In addition, when the E-TFC selecting section 134 b receives therelative transmission rate of the uplink user data (UP command or DOWNcommand) from the non-serving cell for the mobile station UE via theE-RGCH as the scheduling information, the E-TPC selecting section 134 bis configured to increase/decrease the transmission rate of the uplinkuser data, at the timing of receiving the relative transmission rate, bythe predetermined rate based on the relative transmission rate of theuplink user data.

In this specification, the transmission rate of the uplink user data canbe a rate which can transmit an uplink user data via an “EnhancedDedicated Physical Data Channel (E-DPDCH)”, a transmission data blocksize (TBS) for transmitting an uplink user data, a transmission power ofan “E-DPDCH”, or a transmission power ratio (a transmission poweroffset) between an “E-DPDCH” and a “Dedicated Physical Control Channel(DPCCH)”.

As shown in FIG. 11, the layer-1 functional section 135 is provided witha transmission channel encoding section 135 a, a physical channelmapping section 135 b, an E-DPDCH transmitting section 135 c, an E-DPCCHtransmitting section 135 d, an E-HICH receiving section 135 e, an E-RGCHreceiving section 135 f, an E-AGCH receiving section 135 g, a physicalchannel de-mapping section 135 h, a DPDCH transmitting section 135 i, aDPCCH transmitting section (not shown), and a DPCH receiving section 135j.

As shown in FIG. 12, the transmission channel encoding section 135 a isprovided with a FEC (Forward Error Correction) encoding section 135 a 1,and a transmission rate matching section 135 a 2.

As shown in FIG. 12, the FEC encoding section 135 a 1 is configured toperform the error correction encoding processing toward the “uplink userdata (E-DCH)”, that is, the transport block, transmitted from the MAC-efunctional section 134.

In addition, as shown in FIG. 12, the transmission rate matching section135 a 2 is configured to perform, toward the transport block to whichthe error correction encoding processing is performed, the processing of“repetition (repeat of bit)” and “puncture (bit skipping)” in order tomatch to the transmission capacity in the physical channel.

The physical channel mapping section 135b is configured to pair the“uplink user data (E-DCH)” from the transmission channel encodingsection 135 a with the E-DPDCH, and to pair the E-TFI and the HARQinformation from the transmission channel encoding section 135 a withthe E-DPCCH.

The E-DPDCH transmitting section 135 c is configured to perform atransmission processing of the E-DPDCH.

The E-DPCCH transmitting section 135 d is configured to perform atransmission processing of the E-DPCCH.

The E-HICH receiving section 135 e is configured to receive an “E-DCHHARQ Acknowledgement Indicator Channel (E-HICH)” transmitted from theradio base station Node B.

The E-RGCH receiving section 135 f is configured to receive the E-RGCHtransmitted from the radio base station Node B (the serving cell and thenon-serving cell for the mobile station UE).

The E-AGCH receiving section 135 g is configured to receive the E-AGCCHtransmitted from the radio base station Node B (the serving cell for themobile station UE).

The physical channel de-mapping section 135 h is configured to extractthe ACK/NACK for the uplink user data which is included in the E-HICHreceived by the E-HICH receiving section 135 e, so as to transmit theextracted ACK/NACK for the uplink user data to the MAC-e functionalsection 134.

In addition, the physical channel de-mapping section 135 h is configuredto extract the scheduling information (the relative transmission rate ofthe uplink user data, that is, Down command/Don't care command) which isincluded in the E-RGCH received by the E-RGCH receiving section 135 f,so as to transmit the extracted scheduling information to the MAC-efunctional section 134.

In addition, the physical channel de-mapping section 135 h is configuredto extract the scheduling information (the absolute transmission rate ofthe uplink user data) which is included in the E-AGCH received by theE-AGCH receiving section 135 g, so as to transmit the extractedscheduling information to the MAC-e functional section 134.

The DPDCH transmitting section 135 i is configured to perform atransmission processing of a “Dedicated Physical Data Channel (DPDCH)”for uplink user data. The DPDCH is used for transmitting the uplink userdata to be transmitted by the mobile station UE.

Here, the above uplink user data includes a measurement report, whichreports transmission power of a common pilot channel transmitted fromthe cell.

The DPCH receiving section 135 j is configured to perform a receiveprocessing of a “Dedicated Physical Data Channel (DPCH)” for a downlinkuser data transmitted from the radio base station Node B.

Here, the DPCH includes a “Dedicated Physical Data Channel (DPDCH)” anda “Dedicated Physical Control Channel (DPCCH)”.

FIG. 13 shows an example of a configuration of functional blocks of aradio base station Node B according to this embodiment.

As shown in FIG. 13, the radio base station Node B according to thisembodiment is provided with an HWY interface 21, a baseband signalprocessing section 22, a transmitter-receiver section 23, an amplifiersection 24, a transmission-reception antenna 25, and a call processingcontrol section 26.

The HWY interface 21 is configured to receive downlink user data to betransmitted from the radio network controller RNC, which is located inan upper level of the radio base station Node B, so as to enter thereceived downlink user data to the baseband signal processing section22.

In addition, the HWY interface 21 is configured to transmit uplink userdata from the baseband signal processing section 22 to the radio networkcontroller RNC.

The baseband signal processing section 22 is configured perform thelayer-1 processing such as channel encoding processing, spreadingprocessing, and the like, to the downlink user data, so as to transmitthe baseband signal including the downlink user data to thetransmitter-receiver section 23.

In addition, the baseband signal processing section 22 is configured toperform the layer-1 processing such as despreading processing, RAKEcombining processing, error correction decoding processing, and thelike, to the baseband signal, which is acquired from thetransmitter-receiver section 23, so as to transmit the acquired uplinkuser data to the HWY interface 21.

The transmitter-receiver section 23 is configured to convert thebaseband signal, which is acquired from the baseband signal processingsection 22, to radio frequency signals.

In addition, the transmitter-receiver section 23 is configured toconvert the radio frequency signals, which are acquired from theamplifier section 24, to the baseband signals.

The amplifier section 24 is configured to amplify the radio frequencysignals acquired from the transmitter-receiver section 23, so as totransmit the amplified radio frequency signals to the mobile station UEvia the transmission-reception antenna 25.

In addition, the amplifier section 24 is configured to amplify thesignals received by the transmission-reception antenna 25, so as totransmit the amplified signals to the transmitter-receiver section 23.

The call processing control section 26 is configured to transmit/receivethe call processing control signals to/from the radio network controllerRNC, and to perform the processing of condition control of each functionin the radio base station Node B, allocating hardware resource inlayer-3, and the like.

FIG. 14 is a functional block diagram of the baseband signal processingsection 22.

As shown in FIG. 14, the baseband signal processing section 22 isprovided with a layer-1 functional section 221, and a MAC-e functionalsection 222.

As shown in FIG. 15, the layer-1 functional section 221 is provided withan E-DPCCH despreading-RAKE combining section 221 a, an E-DPCCH decodingsection 221 b, an E-DPDCH despreading-RAKE combining section 221 c, abuffer 221 d, a re-despreading section 221 e, an HARQ buffer 221 f, anerror correction decoding section 221 g, a transmission channel encodingsection 221 h, a physical channel mapping section 221 i, an E-HICHtransmitting section 221 j, an E-AGCH transmitting section 221 k, anE-RGCH transmitting section 221 l, a DPDCH transmitting section 221 m, aDPDCH decoding section 221 n, a DPCCH transmitting section (not shown),a DPCCH decoding section (not shown), and a DPCH transmitting section221 o.

However, these functions do not have to be independently present ashardware. That is, these functions can be partly or entirely integrated,or can be configured through a process of software.

The E-DPCCH despreading-RAKE combining section 221 a is configured toperform the despreading processing and RAKE combining processing to theE-DPCCH.

The E-DPCCH decoding section 221 b is configured to decode the E-TFCIfor determining the transmission rate of the uplink user data (or an“Enhanced Transport Format and Resource Indicator (E-TFRI)” based on theoutput from the E-DPCCH despreading-RAKE combining section 221 a, so asto transmit the decoded E-TFCI to the MAC-e functional section 222.

The E-DPDCH despreading-RAKE combining section 221 c is configured toperform the despreading processing to the E-DPDCH using the spreadingfactor (the minimum spreading factor) and the number of multi-codeswhich correspond to the maximum rate that the E-DPDCH can use, so as tostore the despread data to the buffer 221 d. By performing thedespreading processing using the above described spreading factor andthe number of multi-codes, it is possible for the radio base stationNode B to reserve the resources so that the radio base station Node Bcan receive the uplink data up to the maximum rate (bit rate) that themobile station UE can use.

The re-despreading section 221 e is configured to perform there-despreading processing to the data stored in the buffer 221 d usingthe spreading factor and the number of multi-codes which are notifiedfrom the MAC-e functional section 222, so as to store the re-despreaddata to the HARQ buffer 221 f.

The error correction decoding section 221 g is configured to perform theerror correction decoding processing to the data stored in the buffer221 d based on the coding rate which is notified from the MAC-efunctional section 222, so as to transmit the acquired “uplink user data(E-DCH)” to the MAC-e functional section 222.

The transmission channel encoding section 221 h is configured to performthe necessary encoding processing to the ACK/NACK and the schedulinginformation for the uplink user data received from the MAC-e functionalsection 222.

The physical channel mapping section 221 i is configured to pair theACK/NACK for the uplink user data, which is acquired from thetransmission channel encoding section 221 h, with the E-HICH, to pairthe scheduling information (absolute transmission rate), which isacquired from the transmission channel encoding section 221 h, with theE-AGCH, and to pair the scheduling information (relative transmissionrate), which is acquired from the transmission channel encoding section221 h, with the E-RGCH.

The E-HICH transmitting section 221 j is configured to perform atransmission processing of the E-HICH.

In addition, the E-HICH transmitting section 221 j is configured todetermine the transmission power of the E-HICH, based on a first E-HICHoffset or a second E-HICH offset, which are notified from the schedulingsection 222 c, and the transmission power of the downlink DPCH, and totransmit the E-HICH using the determined transmission power.

To be more specific, the E-ITCH transmitting section 221 j is configuredto acquire the transmission power of the downlink DPCH from the DPCHtransmitting section 221 o, and to multiply or add the first E-HICHoffset or the second E-HICH offset, which are notified from thescheduling section 222 c, to the transmission power of downlink DPCH, soas to determine the transmission power of the B-HICH.

The E-AGCH transmitting section 221 k is configured to perform atransmission processing to the E-AGCH.

The E-RGCH transmitting section 221 l is configured to perform atransmission processing to the E-RGCH.

The DPDCH despreading-RAKE combining section 221 m is configured toperform the despreading processing and the RAKE combining processing tothe DPDCH.

The DPDCH decoding section 221 n is configured to decode the uplink userdata transmitted from the mobile station UE, based on the output fromthe DPDCH despreading-RAKE combining section 221 m, so as to transmitthe decoded uplink user data to the MAC-e functional section 222.

Here, the above uplink user data includes a measurement report, whichreports reception power of a common pilot channel transmitted from themobile station UE.

The DPCH transmitting section 221 o is configured to perform atransmission processing to a “Dedicated Physical Channel (DPCH)” fordownlink transmitted from the radio base station Node B.

In addition, the DPCH transmitting section 221 o is configured to notifythe transmission power of the downlink DPCH to the E-HICH transmittingsection 221 j.

As shown in FIG. 16, the MAC-e functional section 222 is provided withan HARQ processing section 222 a, a receive processing command section222 b, a scheduling section 222 c, and a de-multiplex section 222 d.

The HARQ processing section 222 a is configured to receive the uplinkuser data and the HARQ information which are received from the layer-1functional section 221, so as to perform the HARQ processing on the“uplink user data (E-DCH)”.

In addition, the HARQ processing section 222 a is configured to notify,to the layer-1 functional section 221, the ACK/NACK (for the uplink userdata) which shows the result of receive processing on the “uplink userdata (E-DCH)”.

In addition, the HARQ processing section 222 a is configured to notify,to the scheduling section 222 c, the ACK/NACK (for the uplink user data)per process.

The receive processing command section 222 b is configured to notify, tothe re-despreading section 221 e and the HARQ buffer 221 f, thespreading factor and the number of multi-codes for the transport formatof each mobile station UE, which is specified by the E-TFCI per TTIreceived from the E-DPCCH decoding section 221 b in the layer-1functional section 221. Then, the receive processing command section 222b is configured to notify the encoding rate to the error correctiondecoding section 221 g.

The scheduling section 222 c is configured to change the absolutetransmission rate or the relative transmission rate of the uplink userdata, based on the B-TFCI per TTI received from the E-DPCCH decodingsection 221 in the layer-1 functional section 221, the ACK/NACK perprocess received from the HARQ processing section 222 a, theinterference level, and the like.

In addition, the scheduling section 222 c is configured to notify, tothe layer-1 functional section 221, the absolute transmission rate orthe relative transmission rate of the uplink user data, as thescheduling information.

In addition, the scheduling section 222 c is configured to receiveE-HICH offset information which is transmitted from the radio networkcontroller RNC via the HWY interface.

In addition, the scheduling section 222 c is configured to notify thefirst E-HICH offset or the second E-HICH offset, which is included inthe E-HICH offset information, to the layer-1 functional section 221.

The de-multiplex section 222 d is configured to perform the de-multiplexprocessing to the “uplink user data (E-DCH and DCH)” received from theHARQ processing section 222 a, so as to transmit the acquired uplinkuser data to the HWY interface 21.

Here, the above uplink user data includes a measurement report, whichreports reception power of a common pilot channel transmitted from themobile station UE.

The radio network controller RNC according to this embodiment is anapparatus located in an upper level of the radio base station Node B,and is configured to control radio communications between the radio basestation Node B and the mobile station UE.

As shown in FIG. 17, the radio network controller RNC according to thisembodiment is provided with an exchange interface 31, a Logical LinkControl (LLC) layer processing section 32, a MAC layer functionalsection 33, a media signal processing section 34, a radio base stationinterface 35, and a call processing control section 36.

The exchange interface 31 is an interface with an exchange 1, and isconfigured to forward the downlink signals transmitted from the exchange1 to the LLC layer functional section 32, and to forward the uplinksignals transmitted from the LLC layer functional section 32 to theexchange 1.

The LLC layer functional section 32 is configured to perform an LLCsub-layer processing such as a combining processing of a header or atrailer such as a sequence pattern number.

The LLC layer functional section 32 is also configured to transmit theuplink signals to the exchange interface 31 and to transmit the downlinksignals to the MAC layer functional section 33, after the LLC sub-layerprocessing is performed.

The MAC layer functional section 33 is configured to perform a MAC layerprocessing such as a priority control processing or a header addingprocessing.

The MAC layer functional section 33 is also configured to transmit theuplink signals to the LLC layer functional section 32 and to transmitthe downlink signals to the radio base station interface 35 (or themedia signal processing section 34), after the MAC layer processing isperformed.

The media signal processing section 34 is configured to perform a mediasignal processing against voice signals or real time image signals.

The media signal processing section 34 is also configured to transmitthe uplink signals to the MAC layer functional section 33 and totransmit the downlink signals to the radio base station interface 35,after the media signal processing is performed.

The radio base station interface 35 is an interface with the radiobasestation Node B. The radio base station interface 35 is configured toforward the uplink signals transmitted from the radio base station NodeB to the MAC layer functional section 33 (or the media signal processingsection 34) and to forward the downlink signals transmitted from the MAClayer functional section 33 (or the media signal processing section 34)to the radio base station Node B.

The call processing control section 36 is configured to perform a radioresource control processing, a channel setup and release processing bythe layer-3 signaling, or the like. Here, the radio resource controlincludes call admission control, handover control, or the like.

In addition, the call processing control section 36 is configured tonotify the E-HICH offset information to the radio base station Node Bvia the radio base station interface 35.

In addition, as shown in FIG. 17, the call control section 36 isconfigured to store a transmission power ratio between the E-HICH andthe DPCH, as the first E-HICH offset 37 or the second E-HICH offset 37.

Further, the call processing control section 36 is configured togenerate the E-HICH offset information which includes the second E-HICHoffset, when the mobile station UE is performing the SHO, byestablishing the radio links with a plurality of cells.

Furthermore, the call processing control section 36 is configured togenerate the E-HICH offset information which includes the first E-HICHoffset, when the mobile station UE is not performing the SHO, and isestablishing the radio link with one cell.

The radio links according to this embodiment includes the DPCH or theE-DPDCH between the mobile station UE and the radio base station Node B.

Therefore, in this embodiment, the state in which the mobile station UEis establishing the radio link with one cell is indicated as “a Non-SHOstate”, and the state in which the mobile station UE is establishing theradio links with a plurality of cells is indicated as “a SHO state”.

Each of the first E-HICH offset and the second E-HICH offset is thetransmission power ratio between the E-HICH and the DPCH, and it isconfigured that the second E-HICH offset should be greater than thefirst E-HICH offset.

Operations of Mobile Communication System According to First Embodimentof the Present Invention

Referring to FIGS. 18 and 19, operations of the mobile communicationsystem according to this embodiment will be described.

Specifically, the operations of controlling a transmission power of atransmission acknowledgement channel (E-HICH) for uplink user data inthe mobile communication system according to this embodiment will bedescribed.

Here, in this embodiment, examples where a radio base station Node B isconfigured to control one or a plurality of cells, the cells include thefunctions of the radio base station Node B will be described.

As a first example, operation of controlling a transmission power of anB-HICH by a cell #10, when a mobile station UE is shifting from theNon-SHO state, where the radio link with only the cell #10 inestablished, to the SHO state, where the radio links with the cell #10as well as a cell #20 are established, will be described.

In this embodiment, it can be configured that both of cell #10 and cell#20 are controlled by a same single radio base station Node B, or theeach of cell #10 and cell #20 is controlled by different radio basestations Node B.

As shown in FIG. 18, in step S1001, the mobile station UE isestablishing a data connection for transmitting uplink user data withthe radio network controller RNC via the cell #10.

In this case, the cell #10 is configured to determine the transmissionpower of the E-HICH, based on the transmission power of the DPCH and thefirst E-HICH offset.

To be more specific, the cell #10 is configured to multiply or add thefirst E-HICH offset which is included in the E-HICH offset informationtransmitted from the radio network controller RNC in advance, to theDPCH to which the closed loop transmission power control is performed,so as to determine the transmission power of the E-HICH.

In step S1002, when the reception power of the common pilot signal fromthe cell #20 become more than or equal to the predetermined value, themobile station UE transmits a measurement report to the radio networkcontroller RNC.

In step S1003, the radio network controller RNC requests the radio basestation Node B #2 which controls the cell #20 to establishsynchronization of radio links for uplink between the mobile station UEand the cell #20, based on the transmitted measurement report.

To be more specific, the radio network controller RNC transmits a SHOsetting request to the radio base station Node #2 which controls thecell #20, so as to request to establish synchronization of the radiolinks for uplink between the mobile station UE and the cell #20.

The SHO setting request includes a channelization code for identifyingthe channel configuration in the radio link, and a scrambling code foridentifying the mobile station UE.

In step S1004, the radio base station Node B #2 which controls the cell#20 establishes the synchronization of the radio links for uplinkbetween the mobile station UE and the cell #20.

To be more specific, in the radio link for uplink, the radio basestation Node B #2 which controls the cell #20 detects the channeltransmitted by the mobile station UE using the channelization code andthe scrambling code received from the radio network controller RNC, soas to establish the synchronization of the radio links for uplinkbetween the mobile station UE and the cell #20.

When the synchronization of the radio links for uplink between themobile station UE and the cell #20 is established, the radio basestation Node B #2 which controls the cell #20 transmits a SHO settingresponse to the radio network controller RNC. In addition, in thedownlink, the cell #20 starts the transmission of the DPCH and the liketo the mobile station UE.

In step S1005, the radio network controller RNC requests the mobilestation UE to establish synchronization of radio links for downlinkbetween the cell #20 and the mobile station UE.

To be more specific, the radio network controller RNC transmits a SHOsetting request to the mobile station UE, so as to request to establishthe synchronization of radio links or downlink between the cell #20 andthe mobile station UE.

Here, the SHO setting request includes a channelization code foridentifying the channel configuration in the radio link for downlink,and a scrambling code for identifying the cell #20.

In step S1006, the mobile station UE establishes the synchronization ofradio links for downlink between the cell #20 and the mobile station UE.

To be more specific, in the radio link for downlink, the mobile stationUE detects the channel transmitted from the cell #20 using thechannelization code and the scrambling code received from the radionetwork controller RNC, so as to establish the synchronization of theradio links for downlink between the cell #20 and the mobile station UE.

When the synchronization of the radio links for downlink between thecell #20 and the mobile station UE is established, the mobile station UEtransmits a SHO setting response to the radio network controller RNC.

In step S1007, the radio network controller RNC transmits the E-HICHoffset information including the second E-HICH offset, to the radio basestation Node B #1 which controls the cell #10 and the radio base stationNode B #2 which controls the cell #20.

The E-HICH offset information may be transmitted to the radio basestation Node B #2 which controls the cell #20, by the SHO settingrequest.

In step S1008, the cell #10 and the cell #20 determine the transmissionpower of the E-HICH, based on the second E-HICH offset which is includedin the E-HICH offset information transmitted from the radio networkcontroller RNC.

Here, the second E-HICH offset transmitted from the radio networkcontroller RNC is set to be greater than the first E-HICH offset.

Accordingly, when the mobile station UE, i.e., the destination of theE-HICH, is performing the SHO, the cell #10 sets the E-HICH offsetgreater, and to increase the transmission power of the E-HICH, so as toensure the transmission of the E-HICH to the mobile station UE which isperforming the SHO.

As a second example, operation of controlling the transmission power ofthe E-HICH by the cell #10, when the mobile station UE is shifting fromthe SHO state, where the radio links with the cell #10 as well as a cell#20 are established, to the Non-SHO state, where the radio link withonly the cell #10 is established, will be described.

As shown in FIG. 19, in step S2001, when the reception power of thecommon pilot signal from the cell #20 become less than the predeterminedvalue, the mobile station UE transmits a measurement report to the radionetwork controller RNC.

In step S2002, the radio network controller RNC requests the radio basestation Node B #2 which controls the cell #20 to release the radio linksfor uplink between the mobile station UE and the cell #20, based on thetransmitted measurement report.

In addition, the radio network controller RNC transmits a SHO releaserequest to the mobile station UE, so as to release the radio link fordownlink between the cell #20 and the mobile station UE.

In step S2003, the radio network controller RNC transmits the E-HICHoffset information including the first E-HICH offset to the radio basestation Node B #1.

In step S2004, the cell #10, which has received the E-HICH offsetinformation, determines the transmission power of the E-HICH, based onthe first E-HICH offset included in the E-HICH offset information andthe transmission power of the downlink DPCH.

Accordingly, when the mobile station UE, i.e., the destination of theE-HICH, is not performing the SHO, the cell #10 is configured tominimize the E-HICH offset in the Non-SHO state appropriately, and toadjust the transmission power of the E-HICH, so as to use the radionetwork capacity effectively.

In the mobile communication system according to this embodiment, theexample that the radio network controller RNC transmits the E-HICHoffset information including the second E-HICH offset, when the mobilestation UE is performing the SHO, is shown.

However, in the present invention, the radio network controller RNC canbe configured to transmit the E-HICH offset information including thesecond E-HICH offset based on the predetermined notification from themobile station UE and the cell (for example, a predetermined measurementreport from the mobile station UE, and the like).

Effects of Mobile Communication System According to First Embodiment ofthe Present Invention

According to the transmission power control method and the mobilecommunication system of the present invention, it is possible totransmit the E-HICH to the mobile station UE, even when the mobilestation UE is performing the SHO.

In other words, according to the transmission power control method andthe mobile communication system of the present invention, when themobile station UE is performing the SHO, the cell or the radio basestation Node B which controls the cell can set the E-HICH offsetgreater, and increase the transmission power of the E-HICH greater.Therefore, it is possible to ensure the transmission of the E-HICH tothe mobile station UE.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and the representative embodimentsshown and described herein. Accordingly, various modifications may bemade without departing from the scope of the general inventive conceptas defined by the appended claims and their equivalents.

1. A transmission power control method for controlling a transmissionpower of a transmission acknowledgement channel for uplink user datawhich is transmitted from a cell controlled by a radio base station to amobile station, comprising: notifying, from a radio network controllerto at least one radio base station controlling a first cell and a secondcell, offsets between the transmission power of the transmissionacknowledgement channel and a transmission power of a dedicated physicalchannel, when a mobile station is performing a soft-handover with thefirst cell and the second cell; determining, at the first cell, atransmission power of a first transmission acknowledge channel based ona notified offset, and transmitting the first transmission acknowledgechannel to the mobile station using the determined transmission power;and determining, at the second cell, a transmission power of a secondtransmission acknowledge channel based on a notified offset, andtransmitting the second transmission acknowledge channel to the mobilestation using the determined transmission power.
 2. The transmissionpower control method according to claim 1, wherein the radio networkcontroller is configured to notify, to at least one radio base stationcontrolling the first cell and the second cell, the offsets between thetransmission power of the transmission acknowledgement channel and thetransmission power of the dedicated physical channel, when the mobilestation is not performing a soft-handover with the first cell and thesecond cell.
 3. A mobile communication system for controllingtransmission power of a transmission acknowledgement channel for uplinkuser data which is transmitted from a cell controlled by a radio basestation to a mobile station; wherein a radio network controller isconfigured to notify, to at least one radio base station controlling afirst cell and a second cell, offsets between a transmission power of atransmission acknowledgement channel and a transmission power of adedicated physical channel, when a mobile station is performing asoft-handover with the first cell and the second cell, the first cell isconfigured to determine a transmission power of a first transmissionacknowledge channel based on a notified offset, and to transmit thefirst transmission acknowledge channel to the mobile station using thedetermined transmission power, and the second cell is configured todetermine a transmission power of a second transmission acknowledgechannel based on a notified offset, and to transmit the secondtransmission acknowledge channel to the mobile station using thedetermined transmission power.